The invention relates to a process and apparatus for measuring the degree of filament intermingling of an intermingled multifilament yarn, which can be a single- or multi-component yarn.
The methods of measurement used in the field, such as the pin count test and the Interlace Counter, are increasingly proving unsatisfactory, given the standard reached today in intermingling. For instance, the pin count test no longer provides meaningful information at a very high entanglement density and fails completely in the case of continuous intermingling.
DE Offenlegungsschrift 2,839,439 discloses a process and apparatus for measuring the degree of filament intermingled of an intermingled multifilament yarn wherein open zones of the intermingled yarn are expanded and sensed in contactless fashion. To expand the yarn, the yarn is in this case guided over a vaulted transparent plate, and changes in the yarn are detected by means of a photodetector arrangement. This method of measurement permits only batchwise operation. In EP 340 600 the yarn to be monitored is placed on an aspirated conveyor belt and then likewise sensed b means of an optical sensor. The disadvantage with both prior art processes is that, during measurement, the yarn is in contact with mechanical parts and deformed by that contact, which can lead to a corresponding distortion of the measured signal.